SEAC : Statements - Recommendations on the handling of waste material from cattle

Statement

- 7th June 1996

Recommendations on the handling of waste material from cattle

The Committee considered a number of issues in relation to the safe handling and disposal of waste material from cattle.

The Committee noted that there were in effect five streams of material leaving the abattoir namely:

Meat and edible offals
Specified Bovine Material (SBM)
Other non-SBM offals which were not eaten by humans
Blood and gut contents
Water and other waste fluid from cleaning processes

Taking each in turn the Committee noted that it had already made recommendations about meat and edible offals and was content for these to be used for human and pet food provided the SBM was properly removed. In relation to the other non-SBM , the Committee had already made recommendations that mammalian MBM from rendering not be used for animal feed so as to avoid any possible risk of cross contamination leading to mammalian protein being fed to ruminants which could recycle BSE infectivity and perpetuate the disease in cattle. The Committee noted that its recommendations in relation to the removal of SBM and the control on feeding mammalian MBM to farm animals had now been introduced into legislation.

The Committee also noted that in respect of animals over 30 months of age, its recommendation that this material should be compulsorily deboned under controlled conditions had not been introduced but that the Government had instead prohibited the use of any of this material from entering the human food chain.

The Committee also noted that in respect of other animals over 30 months of age for which compensation was payable from the European Community, it was a condition of the European Community schemes as notified to the United Kingdom that the MBM and tallow had to be incinerated. The Committee did not regard this as necessary on scientific grounds but understood that this was considered desirable by the Commission and the Beef Management Committee as part of the overall design of the scheme which was essentially related to market support and the restoration of consumer confidence rather than public health.

In relation to SBMs the Committee noted that the rendering of this material was now undertaken on dedicated lines which were not used for other material other than material destined for incineration. In relation to the MBM produced from SBM the Committee noted that it had made no recommendations other than this material should not be used for human or animal food or agricultural fertiliser and that it had previously been used for landfill. In relation to the tallow produced from SBM the Committee had previously recommended that this should not enter any human or animal food chain other than material which had been processed by the oleochemical industry where the nature of the processing was such that the Committee felt that it was acceptable for the products of that process to be used for animal feed but not human food. The Committee noted that the Scientific Veterinary Committee (ScVC) had concluded that tallow from SBM should not be used even for animal food and that the United Kingdom Government had issued a consultation document proposing that it should not be used and in effect that it should be incinerated.

The Committee noted that blood and gut contents had normally been spread on land. The Committee noted that concern had been expressed about this practice but felt that given the fact that no BSE infectivity had ever been detected in blood and that there was no evidence of horizontal transmission of disease which would suggest that cattle wastes were directly infective to cattle, there was no reason to recommend that this practice should be prohibited or thought to be inadvisable.

Finally in relation to liquid waste from slaughterhouses the Committee noted that this was often discharged to sewers and that sewage sludge could currently be spread on land. The Committee noted that the spreading of sewage sludge on land was an important outlet which not only recycles useful nutrients but also avoids extremely difficult problems which would arise in relation to very large quantities of material if other outlets had to be found. The Committee were however concerned that the material from washing down floors etc in abattoirs could contain small quantities of SBM. The Committee however noted that these would be particulate in nature, e.g. small gobbets of offal and could settle out or be trapped in the waste handling system of the abattoir. The Committee concluded that particles of brain and spinal cord must not leave the abattoir other than as SBM. Therefore, assuming that the particulate matter is retained and disposed of as SBM, the Committee was content for abattoirs to continue to discharge their liquid waste to sewers and for sewage sludge to be disposed of by spreading on land. Any small particulate matter that might pass through the trap would be diluted to such an extent as to pose negligible risk.

The Committee noted that a number of issues arose in relation to the handling of the different classes of tallow and MBM flowing from rendering plants. These involved transport, handling and eventual disposal. The Committee noted that occupational risk was essentially a matter for the ACDP and the HSE who had issued guidelines for specific occupational groups and were in the process of reviewing these and developing new generic guidance. Although different disposal options were now being considered the Committee noted that offals, including SBM and MBM and tallow, were already products which were being handled and transported and that there was no epidemiological evidence to suggest that this presented a risk to any of those engaged in these trades at present. In particular:

Transport

The Committee concluded that decontamination and proper cleaning of vehicles was important but that given the extreme nature of the chemicals which had to be used if chemical disinfection were to be relied upon it was more important to use dilution and washing with large quantities of water and detergent to ensure that vehicles were returned to a suitable state for further use.

Handling

The Committee noted that the evidence suggests that handling of tallow in liquid form would not present a risk. In relation to greaves and in particular MBM the Committee noted that there was a risk of dust inhalation. Steps should be taken to minimise the generation of dust and particles and those exposed should take the same precautions they would in handling any dusty material.

Landfill

The Committee noted that material including MBM from SBMs had until recently been going to landfill. The Committee concluded that even if there had been infectivity in some of the raw SBM it was all now produced by approved rendering processes which were known to reduce substantially the level of BSE infectivity in the resultant MBM. The Committee felt that there was no reasonable scientific argument for saying that landfill should not continue to be an acceptable outlet for MBM of any origin. The Committee noted that MBM from cattle aged over 30 months and from SBM would in future be incinerated but it did not feel that either of these requirements was justified on scientific grounds. The Committee observed that there would certainly be no reasonable grounds for concern at the use of landfill to dispose of MBM which was not derived from SBM and in particular from MBM which had been incorporated into animal feed which could, until 04 April, have been legally fed to farm livestock other than ruminants. There was no doubt that the disposal of this material in this way presented no significant risk. The Committee also agreed that the disposal of any ash from incineration of MBM or tallow could be disposed of by landfill and recalled that it had previously agreed that this material, even when derived from the incineration of SBM derived MBM could be used as agricultural fertiliser provided the chemical analysis of the product showed negligible levels of nitrogen.

The Committee considered that in relation to landfill sites there was no reason to believe that the leachate posed a significant problem but it recommended that sites should be appropriately engineered and managed to minimise leachate migration. The Committee noted that it was the practice from some sites to gather combustible gases either for flaring or for energy generation and concluded that there was no risk either to the environment or people living in the neighbourhood from this practice on sites where MBM or other material which might contain the BSE agent had been buried (including burial of whole carcases as was sometimes done in the early stages of the epidemic).

Incineration

The Committee concluded that incineration, either in power stations or cement kilns (in which temperatures could reach at least 1400ºC) or in dedicated incinerators which reached 850ºC would be sufficient to ensure that there was no risk, either to those exposed to the smoke plume eg those living in the neighbourhood or those living downwind of the plant or in relation to the ash which could safely be landfilled. It was noted that some ash from power stations was used in aggregate and that the method of firing cement kilns inevitably resulted in some ash being incorporated in the final product. The Committee concluded that given the nature of these processes, these and any other uses of the ash were perfectly acceptable even for ash from MBM (and tallow) derived from SBM. In summary , the Committee did not feel that there were any reasons related to BSE which militated against the use of tallow or MBM as a fuel source for either the power generation or cement industries or that required any special precautions to be taken in relation to the protection of the environment either from smoke discharges or from the resulting ash.